ci(deps): bump actions/upload-artifact from 4 to 7

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v4...v7)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/unified-release.yml

@@ -208,7 +208,7 @@ jobs:
         npm run tauri build -- --target ${{ matrix.rust_target }}
     
     - name: Upload Linux artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: desktop-${{ matrix.platform }}
         path: |
@@ -275,7 +275,7 @@ jobs:
         npm run tauri build -- --target ${{ matrix.rust_target }}
     
     - name: Upload Windows artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: desktop-${{ matrix.platform }}
         path: |
@@ -339,7 +339,7 @@ jobs:
         npm run tauri build -- --target ${{ matrix.rust_target }}
     
     - name: Upload macOS artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: desktop-${{ matrix.platform }}
         path: |
@@ -378,7 +378,7 @@ jobs:
         flutter build apk --release --no-pub
     
     - name: Upload Mobile artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: mobile-release
         path: swingmusic_mobile/build/app/outputs/flutter-apk/app-release.apk
@@ -424,7 +424,7 @@ jobs:
         python -m build
     
     - name: Upload Backend artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: backend-package
         path: dist/